[gpaw-users] Wavefunction convergence problem

[Gaël Donval]

Hi Ask,

The smearing temperature is 0.1 eV.

Regards,
Gaël

Le mercredi 16 juillet 2014 à 11:46 +0200, Ask Hjorth Larsen a écrit :
> Hi Gaël
> 
> What is the smearing temperature?
> 
> Best regards
> Ask
> El 16/07/2014 10:37, "Gaël Donval" <gael.donval at cnrs-imn.fr> escribió:
> 
> > Hi,
> >
> > I have generated a quite a big slab (80 atoms, time reversal symmetry
> > only) with ASE and try to perform structure optimization on it.
> >
> >         Unit Cell:
> >                    Periodic     X           Y           Z      Points
> >  Spacing
> >
> > --------------------------------------------------------------------
> >           1. axis:    no    23.278154    0.000000    0.000000   128
> > 0.1819
> >           2. axis:    yes    0.000000    7.679180    0.000000    40
> > 0.1920
> >           3. axis:    yes    0.000000    0.000000    8.145000    48
> > 0.1697
> >
> >
> > I use only one k-point (gamma).
> >
> > When I first tried to get SCF convergence, I couldn't even converge to
> > anything, even with very low mixing parameters. I had to remove bands
> > (from nelectron to 25 unoccupied bands) to get the convergence that you
> > will see bellow.
> >
> > At the first relaxation step, in the SCF calculation, everything
> > converges smoothly down to some point then hits a limit: the error on
> > the density stays around 10^-4 and the error on the wavefunction is
> > switching between two values. For instance:
> >
> >         iter:  47  10:02:07  -3.19  -4.20    -356.939274  2      2
> >         iter:  48  10:02:09  -3.11  -4.13    -356.938830  2      3
> >         iter:  49  10:02:12  -3.19  -4.43    -356.938031  2      2
> >         iter:  50  10:02:14  -3.11  -4.49    -356.937563  2      2
> >         iter:  51  10:02:17  -3.19  -4.60    -356.937381  1      1
> >         iter:  52  10:02:20  -3.11  -4.57    -356.937543  1      1
> >         iter:  53  10:02:22  -3.19  -4.59    -356.938149  1      1
> >         iter:  54  10:02:25  -3.11  -4.56    -356.937988  1      1
> >         iter:  55  10:02:27  -3.19  -4.53    -356.938700  2      2
> >         ...
> >         iter: 283  10:12:19  -3.15  -3.84    -356.893178  2      2
> >         iter: 284  10:12:22  -3.08  -4.34    -356.882750  1      1
> >         iter: 285  10:12:24  -3.15  -4.55    -356.858456  2      2
> >         iter: 286  10:12:27  -3.08  -4.24    -356.864220  2      1
> >
> >
> > If I consider that this is enough and stop there, then I got the same
> > behavior in the second step with the error on the density converging to
> > ~10^-4 *but* the error on the wavefunctions stays at ~10^-1.4 (same
> > behavior, switches between two values).
> >
> > I followed the recommandations on the "Convergence issues" web page,
> > without success. I also tried different mixers and eigensolvers.
> >
> > Does anyone has an idea about that?
> >
> >
> > _______________________________________________
> > gpaw-users mailing list
> > gpaw-users at listserv.fysik.dtu.dk
> > https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
> >


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